\\[-1.8ex] Soil Heterogeneity & $-$0.044$^{**}$ & $-$0.030 & $-$0.036$^{*}$ & $-$0.041$^{*}$ & $-$0.046$^{**}$ & $-$0.048$^{**}$ & $-$0.050$^{**}$ \\ 
  & (0.022) & (0.022) & (0.022) & (0.021) & (0.022) & (0.022) & (0.023) \\ 
\\[-1.8ex]
Observations & 23,431 & 23,431 & 23,431 & 23,431 & 23,431 & 23,431 & 23,431 \\ 
R$^{2}$ & 0.813 & 0.813 & 0.813 & 0.813 & 0.813 & 0.813 & 0.813 \\ 
